In　this　paper,　the　temperature　fields　of　unprotected　and　protected　aluminium-alloy　I-beams　heated　on　three　sides　were　calculated　using　the　finite　element　method.　The　calculated　temperature　results　were　compared　with　the　incremental　temperature　rise　formulas　specified　in　Eurocode　9.　Next,　finite　element　models　were　developed　to　simulate　the　flexural　behaviour　and　the　flexural-torsional　buckling　behaviour　of　aluminium-alloy　I-beams　under　fire.　The　calculated　results　were　validated　by　experimental　data　acquired　at　both　ambient　and　high　temperatures.　Subsequently,　simplified　formulas　for　calculating　critical　temperatures　for　5083-H112　and　6060-T66　aluminium-alloy　beams　were　proposed　based　on　parametric　analysis,　and　the　results　obtained　using　these　formulas　were　compared　against　equivalent　values　calculated　in　accordance　with　Eurocode　9　standards.　In　terms　of　engineering　applications,　findings　indicate　that　increases　in　the　load　level,　the　global　stability　coefficient,　and　the　ratio　of　fireboard　thickness　to　thermal　conductivity　reduce　the　critical　temperatures　of　aluminium-alloy　beams.　In　most　cases,　designs　using　the　method　of　checking　load　bearing　capacity　at　high　temperature　published　in　the　Eurocode　9　would　tend　to　be　conservative.　Finally,　when　the　global　stability　coefficient　was　greater　than　0.8,　the　critical　temperatures　in　some　regions　measured　slightly　higher　than　the　calculated　simplified　value.　Copyright　(c)　2014　John　Wiley　&　Sons,　Ltd.